1. Field of the Invention
The present invention relates to an aquarium filter system. More specifically, the invention relates to a self-cleaning undergravel filter system.
2. Description of Related Art
When maintaining an aquarium it is necessary to periodically remove the particulate debris and organic wastes produced by the fish and aquatic plants in the aquarium in order to maintain a healthy environment for the fish and plants. One common way of accomplishing this is to use an undergravel filter system wherein a screen is placed in the tank so that it is supported just above the bottom thereof. A layer of gravel or similar rock material is then placed on the screen to collect the debris and organic wastes which settle toward the bottom of the tank. Additionally, a means for circulating the water downward through the layer of gravel or similar rock material and the screen is sometimes employed.
When an undergravel filter is in use, the gravel bed acts to filter out the particulate debris and organic wastes in the water while aerobic bacteria within the filter bed convert much of the waste into non-toxic gases. This process in not perfect; the particulate debris and organic waste will eventually collect on the screen and the bottom of the tank in sufficient quantities to affect the environment of the aquarium. This necessitates periodic cleaning of the screen and the bottom of the tank.
Traditionally this requires that the fish and aquatic plants be removed from the tank along with the gravel and screen structure so that the bottom of the tank and the screen structure may be cleaned. Several undergravel filter systems which provide a means for self-cleaning to avoid this inconvenience have been disclosed in the prior art.
U.S. Pat. No. 4,921,614, issued May 1, 1990 to Frickman et al., discloses an undergravel filter system having a slidable cleaning element extending across the width of the tank between the screen structure and the bottom of the tank. The cleaning element pushes the debris collected between the screen and the bottom of the tank to a conduit which draws water and the debris out of the tank where it is disposed or otherwise filtered and returned to the tank. The cleaning element used with the system of Frickman et al. has a metallic bar therein which allows the bar to be moved across the bottom of the tank by a magnetic source such as a hand held magnet placed against the bottom of the tank. While it is generally effective, this means of moving the cleaning element is not practical when the bottom of the tank is not readily accessible as is often the case with domestic aquariums.
U.S. Pat. No. 4,957,623, issued Sep. 18, 1990 to Joseph C. Henzlik, discloses another undergravel filter system having a slidable cleaning element extending across the width of the tank between the screen structure and the bottom of the tank. The cleaning element in the system of Henzlik is in the form of a suction head connected to a siphon tube that urges the suction head across the bottom of the tank as the siphon tube is fed down into the tank through a guide tube. The suction head is generally effective at removing debris from the bottom of the tank, but it does not clean the screen structure.
U.S. Pat. No. 5,197,911, issued Jan. 19, 1993 to Hong-Jien Chow and Yi-Min Jian, discloses a fish tank having an undergravel filter system that has a means for flushing the water and debris from the space between the screen structure and the bottom of the tank. This is accomplished by forcing water into one end of the space between the screen structure and the bottom of the tank through a feed tube and drawing the water out of the opposite end of the space through a tube system leading out of the bottom of the tank.
U.S. Pat. No. 3,759,223, issued Sep. 18, 1973 to Robert D'Andrea, discloses an aquarium including an undergravel. filter system that has a unique structure that allows water and debris collected in the space between the screen structure and the bottom of the tank to be drained for removal of debris from the tank. A drain spigot disposed through the side of the tank adjacent the bottom thereof allows this to be done with little. effort.
U.S. Pat. No. 3,722,685, issued Mar. 27, 1973 to Henry E. Orensten and Vivian C. Orensten, and U.S. Pat. No. 3,785,342, issued Jan. 15, 1974 to George H. Rogers, disclose undergravel filter systems which each employ a pump and filter arrangement to draw the water and debris from between the screen structure and the bottom of the tank for cleaning before returning it to the tank. The system of Orensten returns the water directly to the space between the screen structure and the bottom of the tank so that the water in the tank has a unique circulation pattern while the system of Rogers simply returns the cleaned water to the top of the tank.
U.S. Pat. No. 4,752,388, issued Jun. 21, 1988 to Ying N. Ng, and U.S. Pat. No. 5,066,394, issued Nov. 19, 1991 to Mark R. Harrison disclose undergravel filter systems which have a means of inducing the water to flow through the layer of gravel and the screen structure, through the space between the screen structure and the bottom of the tank, and then back to the main body of the tank. The system of Harrison employs pumps and suction tubes disposed at opposite ends of the tank to induce flow, while the system of Ng induces flow by supplying pressurized air to a tube connecting the space between the screen structure and the bottom of the tank with the main body of the tank. By inducing the water to flow through the space between the screen structure and the main body of the tank, debris will collect there more slowly than undergravel filter systems without induced flow, thus cleaning is required less frequently.
Finally, several devices for scraping debris from an aquarium have been disclosed in the prior art, including U.S. Pat. No. 4,733,427, issued Mar. 29, 1988 to Richard H. Conrad, and U.K. Patent Number 2,105,977, published Apr. 7, 1983. The device of Conrad employs a brush mounted on the end of an elongate handle while the British document discloses a magnetically actuated elongate bar having scraping edges.
However, none of the prior art discloses an undergravel filter system which includes a slidable cleaning element extending across the width of the tank between the screen structure and the bottom of the tank which is actuated by an elongate handle extending from the top of the tank. Furthermore, none of the above inventions and. patents, taken either singly or in combination, is seen to describe the instant invention as claimed.